Heating with Wood - What You Need to Know
Burning wood can release pollutants into the air we breathe, especially when poor burning techniques and wood burning appliances are used.
Breathing in wood smoke can cause increased respiratory symptoms, increased hospital admissions, exacerbation of asthma and COPD, and decreased your ability to breathe normally. If you have a lung disease, breathing in wood smoke can make your disease worst and cause a flare-up.
What's in wood smoke?
Environment Canada and Health Canada have identified many hazardous chemical substances in wood smoke, including:
- PM2.5 (inhalable particulate matter less than 2.5 microns in diameter) - PM2.5, which consists of a mixture of microscopic particles of varied size and composition, has been declared a toxic substance under the Environmental Protection Act. These particles can be inhaled deep into the lungs, leading to serious respiratory problems, including excess mortality, especially among those with pre-existing cardiopulmonary illness.
- Carbon Monoxide (CO) - can reduce the blood's ability to supply necessary oxygen to the body's tissues, which can cause stress to the heart. When inhaled at higher levels, CO may cause fatigue, headaches, dizziness, nausea, confusion and disorientation and, at very high levels, lead to unconsciousness and death. Fire Prevention Canada advises that CO detectors be installed in every home that has a combustion appliance or an attached garage.
- Oxides of Nitrogen (NOx) - can lower the resistance to lung infections. In particular, nitrogen dioxide can cause shortness of breath and irritate the upper airways, especially in people with lung diseases such as emphysema and asthma.
- Hydrocarbons (HC) - can damage the lungs.
- Volatile organic compounds (VOCs) - can cause respiratory irritation and illness. Some VOCs emitted by wood-burning appliances, such as benzene, are known to be carcinogenic.
- Formaldehyde - can cause coughing, headaches and eye irritation and act as a trigger for people with asthma.
- Polycyclic aromatic hydrocarbons (PAHs) - Prolonged exposure to PAH's is believed to pose a cancer risk.
- Dioxins and furans- Some dioxins and furans are carcinogenic.
- Acrolein - can cause eye and respiratory tract irritation.
The Canadian Lung Association recommends that you don't burn wood in residential setting.
However, if you must heat with wood, follow these precautions:
There are many things you can do to reduce the amount of pollution created by residential wood burning, and to improve the safety and efficiency of your wood burning appliance:
- Burn small, hot fires - they produce much less smoke than ones that are left to smoulder.
- Burn seasoned hardwood - burning "green" or wet wood produces significantly more smoke. Soft woods like pine produce more emissions and deposits inside your chimney. Households can buy an inexpensive basic wood moisture meter in a woodworking specialty shop.
- Never burn garbage, plastics, cardboard or Styrofoam. Burning garbage releases poisons.
- Never burn wood that has been taken from salt water. Chlorine combines with the smoke to produce dioxins and furans, which are dangerous carcinogens.
- Never burn treated or painted wood, particleboard or plywood represents a health hazard. Wood treated with varnishes and sealants, wood from orchards sprayed with pesticides and pressure-treated wood may contain toxic chemicals. Burning treated wood may release these toxic chemicals into the environment in the smoke or in the ash that is disposed of later.
- Store wood outside, off the ground and covered. Bring it into your home as needed. The excess moisture found in green wood increases the relative humidity of the indoor air, which can lead to mould and mildew growth. Both can cause severe allergic reactions and asthma attacks.
- Use a high-efficiency wood stove, fireplace or insert that is certified as low emission by the EPA . These wood burning appliances burn most of the smoke right in the firebox and can cut emissions by up to 90 percent. High-efficiency units allow you to burn a third less wood and get the same amount of heat.
- Reduce your heating needs by making your house more energy efficient.
- Regardless of the type of wood-burning appliance, it should be installed by professionals and inspected and cleaned at least once a year by a technician certified under the Wood Energy Technical Training (WETT) Program or, in Quebec, the Association des professionnels du chauffage (APC). These certified installers and chimney sweeps have gone through a rigorous training program that is recognized by the industry and by government.
Municipal Bylaws Regulating Wood Heating
Many municipalities experience air quality problems because of residential wood burning. For municipalities who'd like to develop regulations on wood burning, Canadian Council of Ministers for the Environment has developed resources including Guidance Document for Canadian Jurisdictions on Open-Air Burning (2016)
What about chimineas?
Chimineas are ceramic wood burning appliances that people use outdoors, often on patios. The same concerns apply here as to other open burning. The open design of these devices leads to inefficient burning of the wood. Wood smoke from chimineas may stay closer to the ground since they have low chimney stacks, and can pose a problem for neighbours.